1. Field of the Invention
The present invention relates to a field of liquid crystal display technology, especially to a backlight module and a corresponding liquid crystal display device that the thickness of the direct-type backlight module is reduced.
2. Description of the Related Art
Liquid crystal display devices have been widely used in many kinds of electronic products. Liquid crystal display devices are mostly backlight-type liquid crystal devices that have a liquid crystal panel and a backlight module. Backlight modules are sorted into side-light type and direct-light type based on the incident position of their light sources.
FIG. 1 is a schematic view of a conventional direct-light type backlight module. The direct-light type backlight module includes a backboard 11, multiple light sources 12, a diffuser panel 13 and an optical film 14. The light sources 12 are mounted on the backboard 11. The diffuser panel 13 has a light-receiving surface for receiving lights emitting from the light sources 12. The optical film 14 is used to improve the optical effect of the lights from the diffuser panel 13. The light sources 12 each includes a base 121 (such as a printed circuit board), an LED 122 mounted on the base 121 and a heat sink 123 connected to the base 121 for dissipating heat. The light sources 12 each is connected to the backboard 11 via its heat sink 123. Meanwhile, the backboard 11 has concave portions 111 mounted on an inner surface thereof. The concave portions 111 are relatively protruded out from a back of the backboard 11 so as to be attached to a case of a corresponding liquid crystal display device.
With reference to FIG. 1, the space between the backboard 11 and the diffuser board 13 is called “backlight cavity”, in order to reduce the thickness of the backlight module to satisfy the development of thin liquid crystal display television, people commit themselves to reducing the height of the backlight cavity to reduce the thickness of the backlight module. There are a few known solutions for reducing the height of the backlight cavity:
1. Directly reduce the light-mixing distance D from the light-emitting surface of the light sources 12 to the diffuser panel 13; however this solution will decrease the uniformity of the lights emitted from the backlight module; and
2. Increase the number of the light sources in the backlight module; this solution can relatively reduce the light-mixing distance D from the light-emitting surface of the light sources 12 to the diffuser panel 13 without affecting the uniformity of the lights emitted from the backlight module, but causes an increase in the manufacturing cost of the backlight module.
Hence, it is necessary to provide a backlight module and a corresponding liquid crystal display device to overcome the problems existing in the conventional technology.